Identifying Arachis Amphidiploids Resistant to Foliar Fungal Diseases

Many wild species of the genus Arachis are more resistant to pests and diseases than the cultivated species A. hypogaea. However, the use of Arachis germplasm in breeding programs is hampered by sterility barriers mainly due to differences between the genomes and the ploidy levels of A. hypogaea and related species. The aim of this study was to evaluate eight newly obtained amphidiploids and their parents for resistance to early leaf spot, late leaf spot, and rust under field conditions for three consecutive years. The diseases were evaluated using a diagrammatic scale with visual symptom scores ranging from 1 to 9 for the leaf spots and rust diseases. With few exceptions, all parental wild species accessions and the derived amphidiploids were more resistant than A. hypogaea checks. The amphidiploids with the greatest resistance to the three foliar fungal diseases were (A. magna Krapov., W.C. Gregory & C.E. Simpson V 13751 x A. cardenasii Krapov. & W.C. Gregory GKP 10017)(4x), (A. magna K 30097 x A. stenosperma Krapov. & W.C. Gregory V 15076)(4x), and (A. vallsii V 7635 x A. stenosperma V 10229)(4x). These amphidiploids will be used in crosses and backcrosses with A. hypogaea, with the aim of performing introgression and pyramidization of disease resistance genes in cultivated peanut.